Everyone will be looking up on Monday, August 21, when what’s being called the Great American Eclipse sweeps across the U.S.

“I really encourage you to be in a place where you can see the total solar eclipse,” says Bill Nye, known as the Science Guy from his popular 1990s-era PBS kids’ show. “This one moment where the Earth, moon and sun are in a line—it really is spectacular,” says Nye, 61, who serves as the CEO of the Planetary Society in Pasadena, California, and is star of Bill Nye Saves the World on Netflix.

Check out these eclipse must-knows from Nye and astronomy whiz kids Cannan and Carson Huey-You.

Shadow Bands

The sunlight filtering around the advancing moon creates alternating bands of light and dark on the ground racing across the land. “It’s crazy; they’re several football fields wide, and they move over you. It’s otherworldly and spooky,” Nye says.

Solar Corona

(Alan Dyer/VW Pics/Alamy)

This aura of gasses that surrounds the sun and shoots out into space for millions of miles is spectacularly visible to the unaided eye as a brilliant, glowing halo during the total eclipse.

90 minutes

The amount of time it will take for the eclipse to zoom across the entire continent.

2 minutes and 40 seconds

The longest anyone, anywhere will be able to witness its “totality”—that’s in Hopkinsville, Kentucky.

Follow the stripe

(NASA)

Unlike most other total eclipses, the 2017 eclipse will cross directly overhead—or nearby—many major population areas. “It’s going right across the United States,” Nye says. “Take a felt-tip marker and draw from Oregon to Georgia, and there it is.”

99 years

That’s how long ago the previous coast-to-coast solar eclipse was last seen in the U.S. There will be another total solar eclipse in July 2019, but it will be visible only in parts of Argentina and Chile. The truth is, eclipses aren’t all that rare. “Total solar eclipses occur every two years,” says Nye, author of the just-released Everything All at Once. “They come in pairs. They’re more frequent than presidential elections!” Most are visible only to relatively few people or from places where many people can’t easily go—remote mountaintops, the middle of an ocean, unpopulated areas hundreds or thousands of miles away from anything else. That makes the 2017 eclipse extra special.

Baily’s Beads

(Frank Hollis/Alamy)

During the total eclipse, as the light from the sun is blocked, these points of light begin to appear as sunlight streams through the valleys of the moon’s horizon.

10 Eclipse Must-Knows

In a total eclipse, the moon’s shadow flies across the face of the planet at supersonic speed. That’s fast—almost as fast as it took Carson Huey-You and his younger brother, Cannan, science-minded kid geniuses in the Dallas area, to zip far ahead academically of most kids their age.

(iStock)

Carson, 15, enrolled in Texas Christian University when he was 11 and graduated in May with a degree in physics and minors in math and Chinese. He plans to continue with graduate studies in physics toward a master’s degree and ultimately a doctorate. Cannan, 11, will enter TCU this fall to study engineering and astrophysics.

Here are 10 things Carson and Cannan want you to know about the upcoming eclipse.

Size matters“We are the only planet in our solar system where a moon and our sun have the same apparent sizes in the sky,” says Cannan.

Your pet may be confusedIn the darkness of a total eclipse, animals may think it’s nighttime and begin their evening rituals and sounds. “Some animals and insects get restless and confused,” Cannan says.

Protect your eyes!“Use protective viewing glasses,” says Cannan. “It is safe to look without them only during the short time when the moon completely covers the sun.”

Eclipses to die for“In ancient China, people believed solar eclipses were related to health and the success of the emperor. Not predicting one sometimes meant execution,” says Cannan. That’s quite different from today, when “anyone can watch an accurate simulation of a specific [future] solar eclipse on their iPad,” he says.

Super speedThe moon’s shadow races across the Earth so fast, you’d have to fly at least 1.5 times the speed of sound to keep up with it. “It would be cool to fly that fast in a jet at any time, but especially during a solar eclipse!” says Carson.

Eating the sunThere are many myths and superstitions around eclipses. The Chinese word for solar eclipse is shi, meaning “to eat”—as in the moon eating the sun. “That could be related to the Chinese mythology of a dragon devouring the disc of the sun,” says Cannan.

Cool!Temperatures drop during a solar eclipse. “When the moon covers the sun, less heat is beamed down to the Earth,” says Cannan. “You can expect a temperature drop of about 10 degrees.”

Electrical Grids“During solar eclipses, when the moon covers the sun, solar panels and other devices that depend on sunlight can’t produce any energy,” says Cannan. “Thank goodness most solar eclipses are partial and only viewable from certain locations on Earth,” notes Carson.

A Special PlaceCarbondale, Illinois, got its name “due to the nearby discovery of coal in the 19th century,” says Carson. “The carbon found in coal originated from fusion in stars. The heaviest elements the sun produces in its core are carbon and dioxide.” The point of the 2017 eclipse’s longest duration is only a few miles south of Carbondale—which is also in the path of the next total solar eclipse, in 2024.

Secrets of the StarsHelium, the second lightest element (after hydrogen) was discovered by observing the sun’s corona during a solar eclipse in 1868. “Things like this show just how much we can learn from stars,” says Carson. “Supernovae, black holes and other objects can tell us even more about the universe we live in.”